How did they get this answer?Need a step by step answer (No need for explanation)

Question: f) Calculate the value of (fg)|- in two different ways. Answer 1. a), uj wuv c) (fg) (x) = 6+x-x2 e) domain r ER , range (y y- 2 21 21 f ) ( f8 ) - 2 - 1 - 7 8 = 4 or (f8) -7 - 6+-2) = N 4